This invention relates to novel perfluoropolyether-modified aminosilanes capable of forming cured coatings having water repellency, oil repellency, parting and anti-staining properties, durability and lubricity, surface treating agents comprising the same, and articles having cured coatings of the aminosilanes.
In general, perfluoropolyether-containing compounds have water and oil repellency, chemical resistance, lubricity, parting and anti-staining properties because of their very low surface energy. For the effective utilization of such properties, these compounds are widely used in the industry as water/oil repellent anti-staining agents for paper and fibers, lubricants in magnetic recording media, oil repellants in precision machines, parting agents, cosmetic ingredients, and protective coatings.
The same properties, however, suggest that perfluoropolyether-containing compounds are non-tacky and non-adherent to other substrates. They are applicable to the substrate surface, but cannot form a coating firmly bonded to the substrate.
Silane coupling agents are well known as the means for establishing a firm bond between a substrate surface such as glass or fabric and an organic compound. The silane coupling agent has an organic functional radical and a reactive silyl radical (typically alkoxysilyl radical) in a molecule. The alkoxysilyl radical undergoes self-condensation reaction with air-borne moisture, converting to a siloxane to form a coating. At the same time, the silane coupling agent forms chemical and physical bonds with the surface of glass or metal, resulting in a durable tough coating. By virtue of these advantages, the silane coupling agent is widely used as a coating agent to a variety of substrates.
As one exemplary compound which exhibits the above-mentioned characteristics, JP-A 58-167597 discloses fluoroaminosilane compounds of the following formula (2): 
wherein R1 and R2 each are an alkyl radical of 1 to 4 carbon atoms, Q is CH2CH2CH2 or CH2CH2NHCH2CH2CH2, m is an integer of 1 to 4, and n is 2 or 3. These compounds, however, fail to fully take advantage of the perfluoropolyether radical because the perfluoropolyether radical portion is as short as consisting of two to five monomer units of hexafluoropropylene oxide (HFPO).
Also, JP-A 58-122979 discloses compounds of the following formula (3) as a water and oil repellant to be applied to glass surface. 
Herein, Rf is a polyfluoroalkyl radical having 1 to 20 carbon atoms, which may contain at least one ether bond, R1 is hydrogen or lower alkyl, A is alkylene, x is xe2x80x94CON(R2)xe2x80x94Qxe2x80x94 or xe2x80x94SO2N(R2)xe2x80x94Qxe2x80x94 wherein R2 is lower alkyl and Q is a divalent organic radical, z is lower alkyl, Y is halogen, alkoxy or R3COOxe2x80x94 wherein R3 is hydrogen or lower alkyl, n is 0 or 1, a is 1, 2 or 3, and b is 0, 1 or 2. These compounds do not exert fully satisfactory effects because the number of carbon atoms in the fluorinated radical portion is as small as 1 to 20 carbon atoms.
To solve the above-discussed issues, the inventors proposed in JP-A 11-29585 perfluoropolyether-modified aminosilanes of the following formula (4). 
Herein X is a hydrolyzable radical, R1 is lower alkyl, R2 is hydrogen or lower alkyl, Q is CH2CH2CH2 or CH2CH2NHCH2CH2CH2, m is an integer of 6 to 50, n is 2 or 3, x and y each are an integer of 1 to 3. These perfluoropolyether-modified aminosilanes have improved water repellency, oil repellency, anti-staining, chemical resistance, lubricity, parting and other properties, and can be utilized as a surface treating agent which is applied to the surface of various substrates. However, curing takes a long time because of a lower proportion (in wt %) of hydrolyzable radicals per molecule. Some improvements in film formation were desirable.
To overcome the above drawback, the inventors further proposed in Japanese Patent Application No. 11-139596 perfluoropolyether-modified aminosilanes of the following formula (5). 
Herein X1 and X2 each are a hydrolyzable radical, R1 and R2 each are lower alkyl or phenyl, Q1 and Q2 each are a divalent organic radical, m is an integer of 6 to 50, n is 2 or 3, x and y each are an integer of 1 to 3. It would be desirable to improve the durability and lubricity of these aminosilanes.
Since many tall buildings are constructed in the recent decades, the demand for the technology for imparting xe2x80x9cstain resistancexe2x80x9d or xe2x80x9cease of stain removalxe2x80x9d for keeping glazing maintenance-free is increasing. The same technology is also required in order that display screens be fingerprint-free for better outer appearance and visibility. There is a desire to have a material meeting such demands.
An object of the invention is to provide a perfluoropolyether-modified aminosilane capable of forming a cured coating which firmly bonds to substrates and has improved lubricity and durability. Another object is to provide a surface treating agent comprising the aminosilane and an article having a cured coating of the aminosilane formed thereon.
We have found that a novel perfluoropolyether-modified aminosilane of the following general formula (1) is improved in water repellency, oil repellency, chemical resistance, durability, lubricity, anti-staining and parting properties, can be used as a surface treating agent by applying to the surface of various substrates. A cured coating of the aminosilane is in firm bond to the substrate so that it may sustain the effects over a long period of time.
The present invention provides a perfluoropolyether-modified aminosilane having the formula (1): 
wherein X1 and X2 each are a hydrolyzable radical, R1 and R2 each are a lower alkyl radical or phenyl radical, Q1 and Q2 each are a divalent organic radical, m is an integer of 2 to 50, n is 2 or 3, x is an integer of 1 to 4, and y is an integer of 0 to 4.
The invention also provides a surface treating agent primarily comprising the aminosilane and/or a partial hydrolytic condensate thereof, and an article of manufacture having on its surface a cured coating primarily comprising the aminosilane and/or a partial hydrolytic condensate thereof.
The perfluoropolyether-modified aminosilane of formula (1) serving as a main component of the surface treating agent contains amide linkages. Amide linkages are known effective for efficient orientation of modifying fluoride radicals to the substrate surface. In this regard too, the surface treating agent of the invention is superior to conventional ones. Additionally, the aminosilane of the invention has two hydrolyzable silyl radicals at each end of the molecule so that the ends are firmly bound to the substrate, leading to improvements in lubricity and durability.